V4L/DVB (12805): tm6000: Fix a memory leak at tm6000-video

if a transfer buffer allocation fails, the last allocated urb is leaked
(it hasn't been stored in dev->urb[] yet so tm6000_uninit_isoc misses
it). The patch also includes a small typo fix.

Thanks to Florin Malita <fmalita@gmail.com> for pointing this.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/tm6000/tm6000-video.c

@@ -672,6 +672,7 @@ static int tm6000_prepare_isoc(struct tm6000_core *dev,
 		if (!urb) {
 			tm6000_err("cannot alloc isoc_ctl.urb %i\n", i);
 			tm6000_uninit_isoc(dev);
+			usb_free_urb(urb);
 			return -ENOMEM;
 		}
 		dev->isoc_ctl.urb[i] = urb;